Effect of acidic nano ZSM‐5 modified by hydroxyapatite nanowires on flame‐retardant performance in PLA / IFR composite

Abstract Flame‐retardant polylactic acid (PLA) composites play critical role in construction fields. However, it is urgent to develop flame‐retardant PLA composites since PLA inherent flammability and melt dripping. Herein, we utilize intumescent flame retardant (IFR) with hydroxyapatite nanowires/acidic nano ZSM‐5 (HAP/HN) as synergist to improve the PLA flame‐retardant performance. According to scanning electron microscopy (SEM) observation, HN particles were distributed around with HAP and x‐ray diffraction, Fourier transform infrared spectrum show that the HAP/HN particles were successfully developed with the interaction of hydrogen bonds. The flame‐retardant results of PLA composites showed that the limited oxygen index value increased from 18.0% of neat PLA to 38.2% for HAP/HN sample, moreover the peak heat release rate (pHRR) was lower (~65%) than that of neat PLA (553 kW/m2). In addition, the char yield of PLA/IFR/HAP/HN sample increased from 9.5% to 54.2% for PLA/IFR/HN. SEM results showed that the char surface was smoother and denser with incorporation of HAP/HN. TG‐IR test also demonstrated that the intensity of CO was decreased obviously in gas phase due to the addition of HAP.